Anytime a vehicle, whether it be a ship or an aircraft, travels over a large body of water, there exists a risk that due to an unfortunate occurrence, such as human error, adverse weather, or mechanical failure, passengers and/or crew may find themselves in the water attempting to survive without the vehicle. This may occur far from shore and last for extended periods of time. In such emergency situations, survival depends, in large part, on an individual's ability to stay at the surface of the water to facilitate breathing until assistance can arrive.
Many times, assistance may take several hours or even days to arrive, which may exceed the length of time the individuals in need of rescue are capable of treading water or otherwise physically remaining at the surface under their own power. This is further compounded by the fact that, in many such situations, passengers and/or crew may have sustained injuries during the occurrence that separated them from their vehicle, which may significantly reduce their stamina and/or ability to exert physical effort to remain on the surface of the water. To address this unfortunate contingency, most vehicles that travel over large bodies of water carry personal flotation devices for each individual aboard the vehicle.
The most common form of the personal flotation device is the life vest. A life vest is a positively buoyant device that fits an individual like a vest when properly worn and increases the individual's overall buoyancy such that, at a minimum, the individual's head remains above water without requiring physical effort. In many situations, a properly worn life vest can greatly increase the amount of time an individual can survive while waiting for assistance to arrive.
However, there are some significant drawbacks to life vests. For example, many life vests are constructed from highly buoyant material. Because buoyancy is a function of density, such highly buoyant material is typically very voluminous, making wearing such life vests highly awkward and cumbersome. This, in turn, causes many individuals to forgo wearing a life vest until an emergency situation arises or is immediately foreseeable. This behavior reduces the effectiveness of the life vest because it causes a risk that the individual in need will not be able to locate or properly don the device in time, if an emergency situation materializes rapidly.
This shortcoming has been addressed, in part, by the inflatable life vest. While still inconvenient to wear regularly, inflatable life vests are considerably less awkward and cumbersome to wear, because their buoyancy is derived from an air impermeable bladder that is capable of being inflated when activated, either automatically or manually, but that otherwise remains in a deflated, low-profile position. Because inflatable life vests are considerably less awkward and cumbersome to wear, individuals are much more likely to wear them prophylactically, and therefore, individuals are much more likely to already be properly wearing them when an emergency situation unexpectedly materializes. It is important to note that, generally, when personal protective equipment is not awkward and/or cumbersome, use rates of such equipment tend to rise, and therefore, such equipment is typically more effective at saving lives in practice.
There are additional survival challenges associated with water emergencies that life vests cannot effectively address. Perhaps the most significant challenge is that many of the bodies of water that vehicles regularly cross are of a temperature such that individuals in direct contact with the water would not survive for very long, even if they could manage to keep their heads above water indefinitely. When properly wearing a life vest in the water, an individual's body is almost entirely submerged and in direct contact with the water. Water is very proficient at transferring heat away from an individual's body at a fairly rapid rate. Therefore, prolonged submersion in even mildly cold water can be lethal within a deceptively short period of time.
For example, an average person is only expected to stay conscious for 1-2 hours in water that is between 50 and 60 degrees Fahrenheit. In many water emergency situations, 1-2 hours is far shorter than the amount of time that is required for assistance to arrive, even if the assisting party is aware of the exact location of the individual or individuals in need. In situations where the individual or individuals in need must be located first, rescue times can be considerably longer.
Further, large portions of the earth's ocean are much colder than 50-60 degrees Fahrenheit. This means that if a water related emergency situation arose in those regions, a life vest alone would have little or no ability to increase survivability. There exists a need for an emergency flotation aid that is capable of thermally insulating an individual as well as providing buoyancy.
There have been several attempts to mitigate this thermal limitation to traditional life vests by incorporating some form of thermal insulation. Two examples of such attempted solutions are the float coat and the more extreme survival suit.
A float coat is essentially a thermally insulated jacket that includes an inflatable life vest incorporated within. While a float coat may provide more thermal insulation than the typical life vest, most float coats are primarily designed to thermally insulate an individual from thermal loss caused by air, and therefore, are not designed to be particularly proficient at insulating individuals when submerged in water.
By contrast, survival suits are designed to thermally insulate an individual in water and are very effective at achieving this goal; however, survival suits are also very expensive, bulky, require considerable time get into, and because of their waterproof nature, typically do not breathe adequately to be worn comfortably, making them an unsatisfactory option for prophylactic, low-risk use. There exists a need for a personal flotation device that can provide buoyancy and thermal insulation without causing excessive personal inconvenience while performing low risk activities.
Another legacy solution to this water safety problem is the life raft. A life raft typically provides flotation for several individuals and provides the added benefit of allowing individuals to climb out of the water, thereby significantly reducing the rate of thermal loss due to water. Life rafts do, however, have their limitations as well. The biggest limitation is their typical size. Most life rafts are too large and bulky to be physically attached to or worn by an individual; therefore, while most vehicles that travel across large bodies of water carry a life raft, in order to realize the safety benefits of a life raft, an individual on an ill-fated vehicle must have the opportunity to locate where the life raft is stored, remove the life raft, and deploy the life raft. Depending on the circumstances of the water emergency, this opportunity may not always be available.
The typical inflatable life raft is designed to accommodate approximately 4 people, while larger models used on passenger ships and ferries may hold up to 50 people. Most private vessels, small planes and helicopters venturing offshore carry a life raft with a capacity equal to or greater than the number of crew onboard. A typical life raft on these crafts are in the 4-8 person capacity range. These life rafts are quite heavy, weighing 50-100 lbs and are quite bulky, which makes them difficult to remove from their stored position and similarly difficult to deploy. In a man overboard situation, a rapidly sinking vessel, or the downing of an aircraft over water, there often isn't enough time for victims to wrestle a large, heavy, inflatable life raft out of its stored position and deploy it. This difficulty may leave individuals in direct contact with the water for an extended period of time and prone to hypothermia and/or death.
Most smaller boats and skiffs do not carry life rafts because they are too bulky and too heavy to have onboard. Moreover, one study recorded 28% of fatalities from commercial fishing vessel loss in California, Oregon and Washington between 2000 and 2006 had no raft aboard.
Some pilots carry one man inflatable life rafts in their aircraft, or strap them to their waist. These rafts typically weigh approximately 6-8 lbs. and have an approximate size of 7″ diameter by 12″ long. Their weight and bulkiness make the wearer less agile, particularly when climbing through the small door of a sinking plane or while having to maneuver underwater. Fear of not being able to egress the vehicle in a water emergency or simply preferring to not endure the inconvenience of the safety equipment during normal, low risk operation of the vehicle causes many pilots, aircrew and mariners to forego use of these life rafts.
Other issues with these one man life rafts include their high cost and the difficulty of boarding them once deployed. Climbing over the edge of a legacy life raft can be difficult, especially for those who may have been injured in the incident that caused the water emergency. If an individual deploys a legacy life raft and cannot climb in, they may perish from hypothermia as if they did not have a life raft.
These adverse factors (bulk, weight, cost and boarding difficulty) make legacy life rafts a less than ideal solution for many people including air crewmen, deck personnel on ships of all sizes, sailors, commercial and recreational fishermen and other mariners whose lives could potentially be saved if there existed a lightweight personal water safety device that provided both buoyancy, ease of ingress, and thermal protection. There exists a need for a life raft that is small, lightweight, less expensive and easier to board than the currently available models.
The present disclosure distinguishes over the related art, providing heretofore unknown advantages as described in the following summary.